1. Field of the Invention
This invention relates to mixing of matter and more particularly to an improved static mixer.
2. Background of the Invention
The art of mixing comprises the agitation, distribution, intermingling, and homogeneity of matter. Agitation of matter with the intent to blend is specifically considered to be mixing. Other processes which depend upon and are promoted by agitation and mixing include chemical reactions, heat transfer, dispersion and mass transfer, including both solubility and crystallization. The type, extent and intensity of mixing determine both the process rate and adequacy of the mixing. In all mixing processes, energy must be added in order to effect mixing. Mixing is accomplished by a variety of equipment. Typical of this equipment is the impeller mixer generally used in a closed container and in a batch mixing process. In a continuous mixing process, pipeline blending is a commonly used mixing method. In some continuous process mixing systems, a baffled mixing cell is provided with one or two impellers on a powered shaft.
Static mixers comprise a group of devices comprising motionless devices. These pipe based devices generally contain internal baffles or other devices requiring no external energy to produce a turbulent flow in the pipe other than the energy required to move the matter through the pipe system. Subsequent mixing of the matter therein occurs as the matter is in transit through the pipe system. However, the internal baffles and internal turbulent flow producing devices require additional energy to be applied to the matter traversing the static mixer. The internal baffles also create a non-uniform pressure drop between the inlet and outlet of the system. Additionally, the internal baffles and other internal turbulent flow producing devices may become obstructions to flow. Clean up of these devices when mixing or reacting certain kinds of matter can present significant problems such as polymeric reactions, mixtures of viscous materials and the like. A variety of static mixers has been described in the literature.
U.S. Pat. No. 2,252,045 to Edward Frank Spanner discloses an invention concerned with tubular heat exchange apparatus in which heat transfer is required between hot and cold fluids, and in which the hot fluid i.e. gas or liquid is passed from an inlet chamber to an outlet chamber through a multiplicity of straight tubes expanded into tube plates at the ends of a shell containing or confining the cold fluid i.e. gas or liquid, to which heat is to be transferred.
U.S. Pat. No. 3,337,194 to Zavasnik et al. discloses an in-line blender for particulate materials comprising in combination an elongated chamber having provided therein a plurality of baffle means each so adapted as to partially traverse said chamber thereby obstructing the path flow of solids at one or more points within said chamber.
U.S. Pat. No. 3,612,175 to Ford et al. discloses an improved corrugated metal tubing having an improved heat-transfer coefficient and having a plurality of lands and grooves extending along the circumference thereof. The grooves comprise at least two independent, continuous grooves extending helically along the circumference of the tube, with each groove being in spaced relationship to each other. Improved heat transfer is obtained by providing that the land width, the groove width and the angle of advance of the helically extending grooves are related in a particular defined manner.
U.S. Pat. No. 3,647,187 Dannewitz et al. discloses a static mixer and method of making the same which mixer is capable of simultaneously mixing together a plurality of fluids, usually at least two liquids, in a stream which may be segmented by a fluid which may be a gas, comprising one or more elements forming an elongated fluid passageway for conveying the fluids while at least two liquids are intermixed. A helix is formed within the passageway to impart a rotational movement to the stream so that the rotational velocity at the liquid-wall interface is greater than that at the center of the stream, providing an efficient mixing action, without breaking up the gas segments.
U.S. Pat. No. 3,664,638 to Grout et al. discloses a device for thoroughly mixing components of a fluidic material flowing through a conduit which contains a plurality of curved sheet-like elements extending longitudinally through the conduit in which consecutive elements arc curved in opposite directions and the adjacent edges of consecutive elements are spaced from each other by a distance dependent on the Reynolds number of the fluid and angularly displaced with respect to each other by an angle 20 which differs from 90° by an amount dependent on said distance.
U.S. Pat. No. 3,800,985 to Grout et al. discloses a system for distributing a highly viscous molten material such as a molten polymer. The system includes means for heating the material to a molten state and moving it through a special mixing structure located just ahead of one or more output ports leading to a further processing system including a filament spinneret. The mixing structure includes a conduit containing—a plurality of sheet-like elements extending longitudinally within the conduit, each element being curved to turn the direction of the material flowing past it. The elements are arranged in alternating right and left-handed curvature groups (a group consisting of one or more elements). The conduit is in contact with a heat exchange medium to maintain the polymer at its proper molten temperature. A modification for distributing molten glass is also disclosed as being substantially the same as for the molten polymer.
U.S. Pat. No. 3,908,702 to Klosse et al. discloses portions of fluid components being mixed during transport through a tube by continuously disturbing their flow pattern in a controlled manner during their passage through the tube. The disturbance is created by providing the tube with a radially inward profile that an internal screw-thread of a thickness 0.25 to 0.75 times the internal diameter of the tube and having a pitch 0.75 to 1.5 times the internal diameter of the tube.
U.S. Pat. No. 4,072,296 to Lewis G. Doom discloses a motionless mixer including a number of baffles attached to a central rod is slidably mountable within a hollow cylindrical conduit. A cross member is attached across the interior of the conduit and is configured to mate with a slot formed in the downstream end of the central rod, to prevent longitudinal motion or rotation of the mixer within the conduit.
U.S. Pat. No. 4,093,188 to Terry A. Horner discloses two or more fluids, particularly viscous fluids, may be thoroughly blended and homogenized with a static mixer and method using a mixing element which comprises two or more banks of stationary baffles arranged around an axis parallel to the overall direction of flow of the fluids to be mixed. The baffles in each bank of the element are inclined at an angle to the overall flow axis and at an angle to the baffles of adjacent banks so that fluid streams are guided through windows or apertures formed by abutting baffles along the interface between adjacent banks. Each bank includes a plurality of substantially parallel baffle plates spaced along the axis, and at least one of the banks has a second set of substantially parallel baffle plates spaced along the axis and alternating with the first set of baffles. The baffles of the second set are inclined to the axis at an angle different from the inclination of the baffles of the first set so that alternately converging and diverging passages are formed between the baffles. By this means, fluid streams are successively and repeatedly subdivided, converged and redivided into a plurality of substreams in sinuous, non-parallel spiraling paths to effect a more thorough and efficient blending of the fluids than previously possible.
U.S. Pat. No. 4,112,520 to Oscar Patton Gilmore discloses a static mixer for streams of flowing materials comprising a flow passage defined in a laminated body having end plates and a number of intermediate plates all detachably interconnected to form a unitary structure. The flow passage flows a serpentine path, crossing and recrossing boundaries between the several plates. Mixing structures are formed in the passage for combining, dividing and recombining streams of flowing materials in the passage by means of rotation of flow path and altering the cross-sectional shape of the flow paths. Disassembly of the several plates of the laminated body permits easy access to individual sections of the flow passage to facilitate cleaning and repair. Flow passage sections extend along a path that bends about an axis perpendicular to the direction of flow therein to facilitate mixing and to achieve curvature of the path to enable it is cross and recross the several boundary surfaces between adjacent plates and the laminated body. Flow rotator sections are positioned in intermediate plates to provide a linear flow path. The mixer may employ unique multiple flow rotators either stacked alone or together with flow path bending sections.
U.S. Pat. No. 4,179,222 to Strom et al. discloses a device for generating special turbulence patterns in fluids flowing in pipes, such as for mixing, promoting chemical reactions, or accelerating the transfer of heat to or from the fluid through the pipe wall. Two or more sets of flow dividers are mounted in the pipe, each set including a first and second flow divider with septum panel elements that overlap longitudinally of the pipe. The first flow divider septum elements mutually diverge downstream in a selected longitudinal plane in longitudinally overlapping relationship with septum elements of the second flow divider mutually diverging upstream in a different longitudinal plane so as to divert the fluid in such manner that the flow regions adjoining the pipe wall are caused to exchange positions with flow regions in the vicinity of the pipe axis. By reversing the relative incline angles of the septum elements of corresponding flow dividers of successive sets alternately when a succession of two or more sets are installed in direct series, the desired effects are augmented.
U.S. Pat. No. 4,511,258 to Federighi et al. discloses a motionless mixing device including a conduit having a mixing element therein which is formed by deforming flat stock material. The mixing element includes two substantially identical segments or halves that each having a sinuous cross-section between opposite ends and are interconnected along the center of the conduit with the two segments being axially staggered with respect to each other.
U.S. Pat. No. 4,688,319 to Gross, et al. discloses a method for production of a multi-layer gap-less steel pipe. An inner pipe and an outer pipe are formed from thermomechanically rolled steel strip with high notched bar impact strength by welding. The individual helical welding seam steel pipes of about the same lengths are matched with a difference of less than about one percent between the outer diameter of the inner pipe and the inner diameter of the outer pipe. The matched inner pipe is inserted into the outer pipe and the pipes are mechanically expanded with diameter control to a preset outer diameter of the multi-layer steel pipe. The resulting multi-layer steel pipe has the inner pipe disposed under compression and the outer pipe layer disposed under stress. The presence of a compression stress in the inner pipe provides a means opposed to hydrogen sulfide stress corrosion. The advantages of the helical welding seam steel pipes can be combined such as economic production, advantages relating to crack formation and crack propagation stopping, and the availability of high internal pressure loads upon use of thin, economic steel strip of different yield strength.
U.S. Pat. No. 4,840,493 to Terry A. Horner discloses motionless mixers and baffles thereof and includes a baffle having a pair of substantially symmetric opposing major surfaces generally helically twisted along a central longitudinal axis of the baffle and a first substantially planar surface connecting the pair of major surfaces at one end of the baffle, the first planar surface extending both substantially transversely and substantially parallel to the central longitudinal axis. The intersection of the first planar surface and one of the major surfaces forms a knife-like edge at the one end of the baffle. Similar additional knife-like edges can be provided, a second knife-like edge on the one end of the baffle radially disposed on opposite sides of each of a pair of axes through a central longitudinal axis of the baffle to form leading edges of the baffle and a like pair of knife-like trailing edges on an opposite end of the baffle. Such geometry enables a plurality of the baffles to be formed as a single insert unit by conventional injection molding techniques using only a pair of mold halves.
U.S. Pat. No. 4,865,460 to Juergen Friedrich discloses a static mixing device comprising a conduit located a plurality of rows of spaced parallel tubes extending across the conduit. The tubes are located in rows in which the adjacent rows extend in a longitudinal direction, but are located at right angles to each other. The heat transfer medium flows through the tubes to maintain the product in the conduit within a preselected temperature range. The adjacent rows of tubes abut each other and thus provide a tortuous path for the product in the conduit to effect mixing thereof.
U.S. Pat. No. 4,929,088 to Charles R. Smith discloses a static mixing device adapted to be inserted in a fluid stream having a main flow direction with respect to a closed conduit, comprising at least two tabs inclined in the flow direction at a preselected elevation angle between 10 degrees and 45 degrees to the surface of the conduit. The tabs are spaced apart in a di-reaction transverse to the flow direction, the length and width of the tabs being selected so as to generate pairs of oppositely rotating predominantly streamwise vortices at the tips of each tab, and downstream hairpin vortices interconnecting adjacent streamwise vortices generated by a single tab.
U.S. Pat. No. 4,936,689 to Federighi et al. discloses a static material-mixing apparatus. The static material-mixing apparatus comprises a conduit having an axis and defining a chamber extending longitudinally therethrough opening on first and second ends of the conduit and a mixing element including two continuous segments in the chamber between the first and second ends, each having a generally sinuous cross-section between the first and second ends, the segments being disposed in radially spaced relationship with each other.
U.S. Pat. No. 4,981,368 to Charles R. Smith discloses a method and apparatus for generating tip vortices comprising a series of ramped tabs projecting inward at an acute angle from a bounding surface of a fluid containment and transport vessel such that the tabs are sloped in the direction of the fluid flow and spaced about the internal circumference of the bounding surface transverse to the main flow direction for causing vigorous cross-stream mixing through the generation of paired alternating rotation tip vortices from opposite sides of each tab with the vortices having their axes of rotation along the direction of the main flow. The vigorous cross-stream mixing will accomplish the equalization of various fluid properties such as velocity, thermal energy, kinetic energy and species concentration within the flow.
U.S. Pat. No. 5,069,881 to William J. Clarkin discloses a device and a method for the application of any adhesive. The device includes a hydraulically actuated mixhead which contains means to controllably deliver the components of a polyurethane based adhesive to the point of application of the adhesive and the means to separate between the components until the reaction between them is desired. Typically the components are in the form of streams and comprise an isocyanate stream and a polyol stream, the volume and flow velocity of each of which are in accordance within the invention hydraulically controlled.
U.S. Pat. No. 5,193,588 to Shiro Kanao discloses a pressure-resistant helical corrugated pipe comprising a helical corrugated pipe wall having a top portion, opposite side wall portions and a bottom portion. A continuous thin metal belt plate of a generally U-shaped transverse cross-section is disposed in one of the top portion and the bottom portion and also in at least part of the opposite side wall portions extending from the one of the top portion and the bottom portion. Another metal belt plate of a flat configuration is disposed in the other of the top portion and the bottom portion and disposed out of contact with the thin metal belt plate; and connective belt regions provided between the two metal belt plates in which the metal belt plates are absent. The connective belt regions being made of a synthetic resin or rubber to interconnect the two metal belt plates.
U.S. Pat. No. 5,330,267 to Willy Tauscher discloses a stationary fluid mixer in a flow conduit having at least two baffle plates secured to the wall of the conduit. The baffle plates are wider on the inside of the flow conduit than along the conduit wall, and they form an angle W of 10 degrees to 45 degrees relative to the main flow direction Z. The baffle plates can be given different orientations, and the projection FZ of the baffle plates in the main flow direction through the conduit is between 5 degrees to 30 degrees of the conduit cross-section F. This provides efficient mixing of the fluid in a simple manner.
U.S. Pat. No. 5,758,695 to Ken Carson teaches a hydraulically efficient ribbed pipe, wherein a pipe formed from a continuous, cold rolled, lock seam quality, sheet steel, and having a spiral rib. The pipe may be protected by an abrasion or corrosion resistant coating. The pipe is normally used for storm drains, culverts, sewer lines or HVAC. A closed spiral rib formed in the pipe wall adds strength to the wall, while maintaining a smooth inner wall that promotes exceptionally good fluid flow. The pipe has a smooth interior surface with outwardly projecting structural ribs of helical configuration throughout the length of the pipe.
U.S. Pat. No. 5,800,059 to Cooke, et al discloses a static mixer conduit comprising a longitudinally elongated conduit having tabs that are arranged with respective first edges adjacent the conduit wall, and respective opposed second edges that are spaced radially inwardly from the conduit wall. These tabs are operable as fluid foils so that with fluid flowing through the conduit, greater fluid pressures manifest against the tab's upstream faces relative to reduced fluid pressures against their downstream faces. The resultant pressure difference in the fluid adjacent, respectively, the mutually opposed faces of each of the tabs causes a longitudinal flow of fluid through the conduit over and past each said tab, to be redirected. As a result of that redirection, there is introduced a radial cross-flow component to the longitudinal flow of fluid through the conduit. In particular, the mixer further comprises a central body extending generally coaxially along at least a portion of the longitudinal extent of the conduit and defining between the central bodies surface and the conduit wall, an annular space confining the radial cross-flow. A method is also disclosed, which comprises static mixing, over a longitudinal extent of a mixing volume having an annular cross-section, wherein radial cross-stream mixing in a longitudinal fluid flow results from flow-redirecting tabs redirecting a longitudinal fluid flow from an outer, fluid containment boundary surface, across an intervening space having an annular cross-section towards an inner boundary surface.
In the past, I have used a process of twisting a length of polygonic tubing to produce an ornamental, decorative and non-functional metal work piece. The metal work was used for furniture, fence gates, lamps, table legs and the like. Although I have made, used and sold twisted lengths of polygonic tubing for ornamental, decorative and non-functional metal work pieces, I had no idea that the ornamental, decorative and non-functional metal work piece could be used as a mixing device or a separating device.
In my prior invention as set forth in U.S. patent application Ser. No. 10/167,791 filed Jun. 10, 2002, I set forth a novel static device for mixing matter flowing therethrough. The static device comprises a tube having a polygonic cross section defining a plurality of corners. The tube is spirally twisted with the plurality of corners forming a plurality of helixes for causing the matter flowing through the tube to rotate in accordance with the plurality of helixes. It is an object of the present intention to provide an alternative embodiment to my prior invention to include a center section of the spirally twisted tube formed in an arc having an arc center disposed normal to an axis of the twisted tube.
Another object of this invention is to provide an improved static mixing device which provides substantially reduced flow restriction to matter flowing through device when compared with the prior art.
Another object of this invention is to provide an improved static mixing device which provides a static mixing device.
Another object of this invention is to provide an improved static mixing device for thermally coupling with a container for heat transfer therebetween.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by modifying the invention within the scope of the invention. Accordingly other objects and a full understanding of the invention may be had by referring to the summary of the invention, the detailed description setting forth the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.